Process and apparatus for electrostatic detearing



Dec. 6, 1966 J. SEDLACSIK, JR

PROCESS AND APPARATUS FOR ELECTROSTATIC DETEARING Filed Sept. 10, 1962 2Sheets-Sheet 1 SOLVENT L INVENTOR .rj JOHN SEDLACSIK JR.

ATTORNEY Dec. 6, 1966 J. SEDLACSIK, JR

PROCESS ANIAPPARATUS FOR ELECTROSTATIC DETEARING 2 Sheets-Sheet 2 FiledSept. 10, 1962 I A V INVENTOR JOHN SEDLACSIK JR.

ATTORNEY United States Patent 1 3,290,169 PROCESS AND APPARATUS FORELECTRO- STATIC DETEARING John Sedlacsik, Jr., Garfield, N..I., assignorto Interplanetary Research 8: Development Corp., Garfield,

N.J., a corporation of New Jersey Filed Sept. 10, 1962, Ser. No. 222,417

. 18 Claims. (Cl. 11793.41)

This invention relates to an apparatus for coating articles in anelectrostatic field wherein said articles are first dipped in a bath ofcoating material and then passed through an electrostatic field forremoving excessive coating and tear drops, reference being had toLetters Patent No.1 2,359,476, granted on an application of Charles K.Gravley, October 3, 1944, entitled Electrostatic Method and Apparatus.

In the application of paint, liquid, oil or other coating materials bythe dip process, the excess material which invariably remains at thedrain-off point after substantial flow has ceased, has always been aproblem which has seriously limited widespread application of this mostefficient coating method. The accumulations which remain at thedrain-off points are referred to as tears. In accordance with the abovepatent, a process and apparatus is disclosed which accomplishes theremoval of this excess material and leaves the finish on the articlesmooth and complete. This removal is accomplished by so arranging theapparatus as to cause the dipped articles to pass at the correct timethrough an electrostatic field, wherein an electric force is applied toall parts of the article which tends to pull it towards a spacedelectrode charged at high voltage. If the article is properly held andthe excess coating material is sufficiently liquid, it will be pulledoff the article, leaving a coating that is smooth and free from teardrops or similar excess material. This removal of excess material isherein referred to as detearing.

The present method and apparatus provides a novel electrode which neednot be replaced at any time and which normally will clean itself. In oneform of the invention, should an accumulation of paint or the like behad upon the electrode, it may be easily removed by wiping it therefromwithout the necessity of replacing the entire electrode such as is thecase when the same is made of expanded metal or the like.

Generally there is provided an electrode of circular structure which maybe flat or conical or of any other suitable contour and which iscentrally provided with means for supplying the surface thereof with acontinuous or intermittent flow of a solvent. In one form of theinvention, the electrode is coated with polytetrafiuoroethylene or thelike so that paint or lacquer accumulating thereon may be easily wipedoff. The electrode is provided with simple means for rotating the sameso that as solvent is fed to the electrode and dissolves the paint andthe like which may accumulate thereon, it is removed by centrifugalforce and, in another form of the invention, it is assisted in suchmovement by a fan of novel structure so that at all times the electrodeis substantially clear of accumulations. A tank is provided forcollecting the liquid and means is provided for removing gases from suchtank. Means is provided for draining the tank from time to time as maybecome necessary.

It is accordingly an object of the invention to provide, in anelectrostatic coating apparatus of the character set forth, novel meansand method for removing accumulations of paint or the like from anelectrode forming a part of the invention.

Still another object of the invention is to provide, in an apparatus ofthe character set forth, a novel electrode.

A further object of the invention is to provide, in an 3,290,169Patented Dec. 6, 1966 apparatus of the character set forth, a novelcoating for an electrode forming a part of the invention.

A still further object of the invention is to provide a novel rotatingelectrode forming a part of the apparatus.

A still further object of the invention is to provide, in an apparatusof the character set forth, a novel fan forming a part of the invention.

Other and further objects of the invention will become apparent from areading of the following specification taken in conjunction with thedrawings, in which:

' FIGURE 1 is a fragmentary elevational view, partly broken away andpartly schematic illustrating an endless conveyor and articles carriedthereby to be treated in accordance with the present invention,

FIGURE 2 is a fragmentary vertical sectional view, partly in elevationand partly schematic, illustrating an apparatus in accordance with thepresent invention,

FIGURE 3 is a plan view, partly schematic, of the apparatus illustratedin FIGURE 2,

FIGURE 4 is an enlarged fragmentary vertical sectional view illustratinga modified form of electrode, and

FIGURE 5 is a view similar to FIGURE 4 but illustrating a still furthermodification the invention may assume.

Referring more particularly to the drawings, there is shown therein, inFIGURE l, a series of articles 10 mounted at the lower end of supportmembers 11 carried in longitudinally spaced relation by an endlesscarrier indicated at 12 which carrier is electrically grounded, asindicated at 13.

In carrying out the invention, there is provided an elongated tank 14having an open top 15 immediately over which the articles 10 are adaptedto pass, as indicated in FIGURE 3. The tank is provided with one or morestations generally indicated at 16 which stations are longitudinallyspaced from one another if more than one is provided. These stations arespaced at a distance to allow time for the coating material on the partsto sag to the edge prior to application of high voltage at the nextstation.

In the form of the invention illustrated in FIG. 2, the station 16comprises a casing 17 extending from the bottom of the tank 14, thecasing having a top 17a of insulating material, in which casing 17 uponbase 18 there is mounted standard 19 of insulating material whichprotrudes upwardly through casing 17 and which is provided at its upperend with a metallic support 19a carrying air driven motor 20 connectedby air pipe 21 of insulating material which extends downwardly throughcasing 17 to a conventional air pump 22. The motor 20 is adapted torotate a shaft 23 atop which is affixed a fiat circular metallicelectrode 24. The shaft is centrally provided with a longitudinalopening 25 which communicates at its upper end with an opening 26 in theplate-electrode 24. Fan blades 27 are radially alfixed to the undersideof the plate 24.

A longitudinally extending opening 28 is provided in the support andcommunicates at its upper end with the opening 25 and at its lower endwith a solvent supply pipe 29 of insulating material .which' extendingdownwardly through the casing 17 to a pump 30 which communicates bymeans of a pipe 31 with a tank of solvent 32. The pump 30, the solventtank 32 and connecting lines therebetween are normally isolated from theground depending upon the conductivity of the solvent being used orunless the tank is made of non-conductive material.

The support 19a which is of metallic construction, is connected by awire 33 to a source of high voltage 34 which is grounded, as indicatedM35. The wire 33 extends downwardly through the insulated top 17a ofcasing 17 from its connection, as indicated at 36, with the support 19aand it will be noted that the source of high voltage is at a pointremote from'the tank 14.

In the event that two or more stations 16 are utilized in the apparatus,it will be apparent that a common source of high voltage may beutilized, as indicated at FIGURE 3.

To remove fumes which may accumulate above the tank 14, an exhaust pipe37 having an exhaust fan 38 therein is provided for removing such fumesto a remote place.

When used liquid, indicated at 39, accumulates in the tank 14 it may beremoved therefrom by means of a spigot 40 mounted in the lower portionof the tank 14.

In operation, it will be apparent that the disc-electrode 24 is adaptedto be slowly rotated by means of the airmotor 20, the latter beingsupplied with compressed air to the pipe 21 through the pump 22. At thesame time or from time to time if so desired, solvent is being pumpedfrom the solvent tank 32 through the pipes 31 and 29 by means of thepump 30 through the passages 28 and 25 to the central opening 26 in thedisc 24. As the solvent emerges through the opening 26 it will moveoutwardly upon the surface of the disc 24 dissolving any paint, lacqueror the like which may have been deposited thereon through theelectrostatic forces above mentioned after which it will, throughcentrifugal force, move the thus dissolved paint or the like entirelyfrom the disc 24 where it will fall by gravity into the lower portion ofthe tank 14 accumulating as indicated at 39. Whenever desired, this maybe removed by means of the spigot 40. Meantime, fumes which mayaccumulate above the surface of the liquid solvent in the tank 14 may beremoved continuously by means of the pipe 37 and exhaust pump 38.

It will be understood that as tears accumulate upon the lower endportions of the articles 10 by gravity that they will be drawn by theelectrostatic field and attracted to the surface of the rotating disc 24after which such accumulation is dissolved as heretofore described.

In a modified form of the invention as shown in FIG- URE 4, the uppersurface of the disc 24 is provided with a coating 41 of tefion or thelike. In this case, whenever particles have accumulated upon the uppersurface of the disc 24 and have not been removed through the combinedaction of the solvent and centrifugal forces as above described, theremaining accumulation upon the disc 24 may be removed merely by wipingthe upper surface of the teflon coating since the coating material willnot adhere thereto.

In FIGURE there is shown a further modification the invention mayassume. In this case, instead of the flat disc structure shown inFIGURES 2 to 4, inclusive, there is provided a generally conicalelectrode 42 terminating in a neck 43 at its lower end. In this case theopening 28 in the standard 19 communicates at its upper end with a tube44 the upper end of which is bent, as indicated at 45, to terminate inclose proximity to the interior surface of the member 42. If desired,and as shown, the interior surface of the member 42 may be coated withteflon, as indicated at 46, for the same purposes as above describedwith reference to the coating 41 illustrated in FIGURE 4. Again withreference to the showing in FIGURE 5, it will be apparent that solventis pumped through the tube or nozzle 44 and deposited upon the interiorof the member 42 whereupon it will rise and flow toward the upperperiphery of the member 42 by centrifugal forces and thereafterdischarge therefrom into the tank 14 likewise by such forces thusdissolving particles of paint which have been deposited thereon by theaforesaid electrostatic forces in the same manner as above describedwith reference to the showing, for example, in FIGURES 2 and 4.

Referring again to FIGURE 5, the tube 42 may terminate as indicated indotted lines at 45a near the upper periphery of the innner surface ofthe electrode 42 in which case the electrode will be moved at a low rateof speed to allow the solvent to travel downwardly over the inner faceof the electrode thus cleaning the same after which it will drop bygravity through the open lower end of the electrode into the tank 14.Alternatively or in conjunction with the tube 45a a tube may bepositioned as indicated in dotted lines at 45b to direct a flow ofsolvent against the upper portion of the outer surface of the electrodeto thus flow downwardly on the outer face of the same as it slowlyrevolves to thus maintain the outer surface or, if used in conjunctionwith a tube as at 45a, to clean both surfaces of the electrode 42.

It will be understood that the electrodes 24 and 42 will be rotated at aspeed sufiicient to remove any material which may have been depositedthereon. It will also be seen that the fan blades 27 will assist inmoving matter discharged from the electrodes away from the standard 19and its associated parts. It is also contemplated that the solvent maybe fed periodically or continuously as desired and that the electrodeslikewise may remain stationary for predetermined periods of time if sodesired. The electrodes may be made of conductive or semi-conductivematerials, may be directly or indirectly charged and may be providedwith ribbed or corrugated as well as smooth surfaces.

It will also be apparent that the motor 20 may be repeatedly reversed byconventional means to thus cause the electrode 24 or 42, as the case maybe, to oscilate continuously or periodically.

It is to be understood that the electrodes 24 or 42 may be charged bydirect contact with the high voltage source 34 or may be indirectlycharged by a grid or any suitable remote charging means.

While but certain forms of the invention have been shown and describedherein, it will be readily apparent to those skilled in the art thatmany minor modifications may be made without departing from the spiritof the invention or the scope of the appended claims.

What is claimed is:

1. The method of detearing paint and the like from freshly coatedarticles comprising providing an electrode adjacent said articles,establishing an electrostatic field between said articles and saidelectrode of sufficient intensity to remove excess paint from saidarticles and deposit said excess paint on said electrode, periodicallyfeeding solvent to the central portion of said electrode, andperiodically moving said electrode sufiiciently to distribute saidsolvent over the surface thereof whereby to dissolve and remove coatingelectrostatically deposited from said articles upon said electrode.

2. The method of detearing paint and the like from freshly coatedarticles comprising providing a plurality of electrodes adjacent saidarticles, establishing an electrostatic field between said articles andsaid electrodes, periodically feeding solvent to the central portions ofsaid electrodes, and rotating said electrodes to distribute said solventover the surfaces thereof whereby to dissolve and remove coatingelectrostatically deposited from said articles upon said electrodes.

3. The method of detearing liquid from objects comprising positioning anelectrode adjacent said articles, electrostatically charging saidelectrode, periodically supplying solvent to the surface of saidelectrode, and intermittently rotating said electrode to remove liquidelectrostatically deposited thereon.

4. The method of detearing liquid from objects comprising positioning anelectrode adjacent said articles, electrostatically charging saidelectrode, periodically supplying solvent to the surface of saidelectrode, and intermittently oscillating said electrode to removeliquid electrostatically deposited thereon.

5. Apparatus for removal of excess coating material from articles, saidapparatus comprising an open tank,

means for suspending freshly-coated articles over said.

tank, an electrostatic detearing station mounted in said tankimmediately below said articles, said station including a standardmounted in said tank, a vertical shaft rotatably mounted in saidstandard, a motor mounted on said standard for rotating said shaft, acircular electrode mounted atop said shaft, with a collecting surfacethereof facing said articles, said electrode and said shaft havingcentral communicating openings therein, and means for feeding solventthrough said openings, to the collecting surface of said electrode.

6. Apparatus as defined in claim 5 wherein the electrode is disc-shaped.

7. Apparatus as defined in claim 5 wherein the electrode is disc-shapedand has fan blades aflixed to the bottom side thereof.

8. Apparatus as defined in claim 5 wherein the electrode has a coatingof polytetrafiuoroethylene on at least the upper surface thereof.

9. Apparatus as defined in claim 5 wherein said electrode is conical.

10. Apparatus for the removal of excess coating material from articles,said apparatus comprising an opentopped tank, means for suspendingfreshly coated articles over said tank, an electrostatic detearingstation mounted in said tank immediately below said articles, saiddetearing station including a detearing electrode, means for creating anelectrostatic field between said electrode and said articles for theattraction of excess coating material on said articles to saidelectrode, and drive means for moving said electrode with sufiicientforce to fling from said electrode coating material attracted theretofrom said articles.

11. Apparatus as defined in claim wherein said electrode has a coatingof polytetrafiuoroethylene.

12. Apparatus for the removal of excess coating material from articles,said apparatus comprising an opentopped tank, means for conveyingfreshly coated articles over said tank, an electrostatic detearingstation mounted in said tank immediately below said articles, saiddetearing station including a detearing electrode, means for creating anelectrostatic field between said electrode and said articles for theattraction of excess coating material on said articles to saidelectrode, and drive means for rota-ting said electrode with sufiicientforce to fling from said electrode coating material attracted theretofrom said articles.

13. Apparatus for the removal of excess coating material from articles,said apparatus comprising an opentopped tank, means for conveyingfreshly coated articles over said tank, a plurality of electrostaticdetearing stations mounted in said tank immediately below said articles,said detearing stations each including a detearing electrode, means forcreating an electrostatic field between said electrodes and saidarticles for the attraction of excess coating material on said articlesto said electrodes, and drive means for rotating said electrodes withsufiicient force to fling from said electrodes coating materialattracted thereto from said articles.

14. Apparatus for the removal of excess coating material from articles,said apparatus comprising an opentopped tank, means for suspendingfreshly coated articles over said tank, an electrostatic detearingstation mounted in said tank immediately below said articles, saiddetearing station including a detearing electrode, means for creating anelectrostatic field between said electrode and said articles for theattraction of excess coating material on said articles to saidelectrode, and coating removing means associated with said detearingstation for removing from said electrode coating materialelectrostatically attracted onto said electrode from said articles, saidcoating removing means including a motor mounted Within said tank, avertical shaft operatively coupled to said motor for rotation thereby,and means mounting said electrode on said shaft for rotation of saidelectrode at a rate sufiicient to fling therefrom into said tank coatingmaterial electrostatically attracted to said electrode from saidarticles.

15. Apparatus as defined in claim 14 wherein said electrode is coatedwith polyfluoroethylene.

16. Apparatus as defined in claim 14 wherein said electrode is hollowand circular in horizontal crosssection 17. Apparatus as defined inclaim 14 wherein said electrode is disc-shaped.

18. Apparatus as defined in claim 17 wherein said electrode has a fanblade aflixed to the bottom side thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,359,476 1/ 1940Gravley 117-93 .41 2,444,144 6/ 1948 Ransburg. 2,945,472 1/1956Gengenbach et al.

117-93.41 X 3,128,201 4/ 1964 Gauthier 118-628 X ALFRED L. LEAVITT,Primary Examiner.

RICHARD 1?. NEVIUS, A. GOLIAN,

atssisrqnt Examiners,

1. THE METHHOD OF DETEARING PAINT AND THE LIKE FROM FRESHLY COATEDARTICLES COMPRISING PRROVIDING AN ELECTRODE ADJACENT SAID ARTICLES,ESTABLISHING AN ELECTROSTATIC FIELD BETWEEN SAID ARTICLES AND SAIDELECTRODE OF SUFFICIENT INTENSITY TO REMOVE EXCESS PAINT FROM SAIDARTICLES AND DEPOSIT SAID EXCESS PAINT ON SAID ELECTRODE, PERIODICALLYFEEDING SOLVENT TO THE CENTRAL PORTION OF SAID ELECTRODE, ANDPERIODICALLY MOVING SAID ELECTRODE SUFFICIENTLY TO DISTRIBUTE SAIDSOLVENT OVER THE SURFACE THEREOF WHEREBY TO DISSOLVE AND REMOVE COATINGELECTROSTATICALLY DEPOSITED FROM SAID ARTICLES UPON SAID ELECTRODE.